package be.kuleuven.thesis.widget;

import java.math.BigDecimal;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Parcelable;
import android.view.MotionEvent;
import android.widget.ImageView;
import be.kuleuven.thesis.R;

/**
 * Widget that lets users select a minimum and maximum value on a given numerical range.
 * The range value types can be one of Long, Double, Integer, Float, Short, Byte or BigDecimal.
 * 
 * @author Stephan Tittel (stephan.tittel@kom.tu-darmstadt.de)
 * @author Peter Sinnott (psinnott@gmail.com)
 *
 * @param <T> The Number type of the range values. One of Long, Double, Integer, Float, Short, Byte or BigDecimal.
 */
public class RangeSeekBar<T extends Number> extends ImageView {
	private final Paint paint = new Paint();
    private final Bitmap leftThumbImage = BitmapFactory.decodeResource(getResources(), R.drawable.leftthumb);
    private final Bitmap rigthtThumbImage = BitmapFactory.decodeResource(getResources(), R.drawable.rightthumb);
    //private final Bitmap thumbPressedImage = BitmapFactory.decodeResource(getResources(), R.drawable.leftthumb);
    private final Bitmap seekBarImage;
    private final Handler handler;
    private final float thumbWidth = leftThumbImage.getWidth();
    private final float thumbHalfWidth = 0.5f * thumbWidth;
    private final float thumbHalfHeight = 0.5f * leftThumbImage.getHeight();
    private final float lineHeight = 0.8f * thumbHalfHeight;
    private final float padding = thumbHalfWidth;
    private final T absoluteMinValue, absoluteMaxValue;
    private final NumberType numberType;
    private final double absoluteMinValuePrim, absoluteMaxValuePrim;
    private double normalizedMinValue = 0d;
    private double normalizedMaxValue = 1d;
    private Thumb pressedThumb = null;
    private boolean notifyWhileDragging = false;
    private OnRangeSeekBarChangeListener<T> listener;

    /**
     * Creates a new RangeSeekBar.
     * @param absoluteMinValue The minimum value of the selectable range.
     * @param absoluteMaxValue The maximum value of the selectable range.
     * @param context
     * @throws IllegalArgumentException Will be thrown if min/max value type is not one of Long, Double, Integer, Float, Short, Byte or BigDecimal.
     */
    public RangeSeekBar(T absoluteMinValue, T absoluteMaxValue, Context context, int seekBarId, Handler handler) throws IllegalArgumentException {
            super(context);
            this.absoluteMinValue = absoluteMinValue;
            this.absoluteMaxValue = absoluteMaxValue;
            if(seekBarId == 0)
            	this.seekBarImage = null;
            else this.seekBarImage = BitmapFactory.decodeResource(getResources(), seekBarId);
            this.handler = handler;
            absoluteMinValuePrim = absoluteMinValue.doubleValue();
            absoluteMaxValuePrim = absoluteMaxValue.doubleValue();
            numberType = NumberType.fromNumber(absoluteMinValue);
    }

    public boolean isNotifyWhileDragging() {
            return notifyWhileDragging;
    }

    /**
     * Should the widget notify the listener callback while the user is still dragging a thumb? Default is false.
     * @param flag
     */
    public void setNotifyWhileDragging(boolean flag) {
            this.notifyWhileDragging = flag;
    }

    /**
     * Returns the absolute minimum value of the range that has been set at construction time.
     * @return The absolute minimum value of the range.
     */
    public T getAbsoluteMinValue() {
            return absoluteMinValue;
    }

    /**
     * Returns the absolute maximum value of the range that has been set at construction time.
     * @return The absolute maximum value of the range.
     */
    public T getAbsoluteMaxValue() {
            return absoluteMaxValue;
    }

    /**
     * Returns the currently selected min value.
     * @return The currently selected min value.
     */
    public T getSelectedMinValue() {
            return normalizedToValue(normalizedMinValue);
    }

    /**
     * Sets the currently selected minimum value. The widget will be invalidated and redrawn.
     * @param value The Number value to set the minimum value to. Will be clamped to given absolute minimum/maximum range.
     */
    public void setSelectedMinValue(T value) {
            // in case absoluteMinValue == absoluteMaxValue, avoid division by zero when normalizing.
            if (0 == (absoluteMaxValuePrim - absoluteMinValuePrim)) {
                    setNormalizedMinValue(0d);
            }
            else {
                    setNormalizedMinValue(valueToNormalized(value));
            }
    }

    /**
     * Returns the currently selected max value.
     * @return The currently selected max value.
     */
    public T getSelectedMaxValue() {
            return normalizedToValue(normalizedMaxValue);
    }

    /**
     * Sets the currently selected maximum value. The widget will be invalidated and redrawn.
     * @param value The Number value to set the maximum value to. Will be clamped to given absolute minimum/maximum range.
     */
    public void setSelectedMaxValue(T value) {
            // in case absoluteMinValue == absoluteMaxValue, avoid division by zero when normalizing.
            if (0 == (absoluteMaxValuePrim - absoluteMinValuePrim)) {
                    setNormalizedMaxValue(1d);
            }
            else {
                    setNormalizedMaxValue(valueToNormalized(value));
            }
    }

    /**
     * Registers given listener callback to notify about changed selected values.
     * @param listener The listener to notify about changed selected values.
     */
    public void setOnRangeSeekBarChangeListener(OnRangeSeekBarChangeListener<T> listener) {
            this.listener = listener;
    }

    /**
     * Handles thumb selection and movement. Notifies listener callback on certain events.
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                    pressedThumb = evalPressedThumb(event.getX());
                    invalidate();
                    break;
            case MotionEvent.ACTION_MOVE:
                    if (pressedThumb != null) {
                            if (Thumb.MIN.equals(pressedThumb)) {
                                    setNormalizedMinValue(screenToNormalized(event.getX()));
                            }
                            else if (Thumb.MAX.equals(pressedThumb)) {
                                    setNormalizedMaxValue(screenToNormalized(event.getX()));
                            }
                            if (notifyWhileDragging && listener != null) {
                                    listener.rangeSeekBarValuesChanged(getSelectedMinValue(), getSelectedMaxValue());
                            }
                            Message message = handler.obtainMessage(1, (Integer) getSelectedMinValue(), (Integer) getSelectedMaxValue());
                            handler.sendMessage(message);
                    }
                    break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                    pressedThumb = null;
                    invalidate();
                    if (listener != null) {
                            listener.rangeSeekBarValuesChanged(getSelectedMinValue(), getSelectedMaxValue());
                    }
                    break;
            }
            return true;
    }

    /**
     * Ensures correct size of the widget.
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            int width = 200;
            if (MeasureSpec.UNSPECIFIED != MeasureSpec.getMode(widthMeasureSpec)) {
                    width = MeasureSpec.getSize(widthMeasureSpec);
            }
            int height = leftThumbImage.getHeight()*2;
            if (MeasureSpec.UNSPECIFIED != MeasureSpec.getMode(heightMeasureSpec)) {
                    height = Math.min(height, MeasureSpec.getSize(heightMeasureSpec));
            }
            setMeasuredDimension(width, height);
    }

    /**
     * Draws the widget on the given canvas.
     */
    @Override
    protected void onDraw(Canvas canvas) {
    	super.onDraw(canvas);
    	if(seekBarImage == null) {
    		// draw seek bar background line
    		RectF rect = new RectF(padding, 0.5f * (getHeight() - lineHeight), getWidth() - padding, 0.5f * (getHeight() + lineHeight));
    		paint.setStyle(Style.FILL);
    		paint.setColor(Color.GRAY);
    		canvas.drawRect(rect, paint);
    		// draw seek bar active range line
    		rect.left = normalizedToScreen(normalizedMinValue);
    		rect.right = normalizedToScreen(normalizedMaxValue);
    		// orange color
    		paint.setColor(Color.rgb(255, 165, 0));
    		canvas.drawRect(rect, paint);
    	} else  {
    		int factor = new Float((seekBarImage.getWidth()-padding)/getWidth()).intValue();
    		Bitmap scaledSeekBar = Bitmap.createScaledBitmap(seekBarImage, new Float(getWidth()-padding).intValue(), seekBarImage.getHeight()*factor, true);
    		canvas.drawBitmap(scaledSeekBar, padding, 0.5f * (getHeight() - scaledSeekBar.getHeight()), paint);
    	}
    	// draw minimum thumb
    	drawThumb(normalizedToScreen(normalizedMinValue), Thumb.MIN.equals(pressedThumb), canvas, leftThumbImage);
    	// draw maximum thumb
    	drawThumb(normalizedToScreen(normalizedMaxValue), Thumb.MAX.equals(pressedThumb), canvas, rigthtThumbImage);
    }

    /**
     * Overridden to save instance state when device orientation changes. This method is called automatically if you assign an id to the RangeSeekBar
     * widget using the {@link #setId(int)} method. Other members of this class than the normalized min and max values don't need to be saved.
     */
    @Override
    protected Parcelable onSaveInstanceState() {
            Bundle bundle = new Bundle();
            bundle.putParcelable("SUPER", super.onSaveInstanceState());
            bundle.putDouble("MIN", normalizedMinValue);
            bundle.putDouble("MAX", normalizedMaxValue);
            return bundle;
    }

    /**
     * Overridden to restore instance state when device orientation changes. This method is called automatically if you assign an id to the RangeSeekBar
     * widget using the {@link #setId(int)} method. 
     */
    @Override
    protected void onRestoreInstanceState(Parcelable parcel) {
            Bundle bundle = (Bundle) parcel;
            super.onRestoreInstanceState(bundle.getParcelable("SUPER"));
            normalizedMinValue = bundle.getDouble("MIN");
            normalizedMaxValue = bundle.getDouble("MAX");
    }

/**
     * Draws the "normal" resp. "pressed" thumb image on specified x-coordinate.
     * @param screenCoord The x-coordinate in screen space where to draw the image.
     * @param pressed Is the thumb currently in "pressed" state?
     * @param canvas The canvas to draw upon.
     */
    private void drawThumb(float screenCoord, boolean pressed, Canvas canvas, Bitmap image) {
    	//canvas.drawBitmap(pressed ? thumbPressedImage : leftThumbImage, screenCoord - thumbHalfWidth, (float) ((0.5f * getHeight()) - thumbHalfHeight), paint);
    	canvas.drawBitmap(image, screenCoord - thumbHalfWidth, (float) ((0.5f * getHeight()) - thumbHalfHeight), paint);
    }

    /**
     * Decides which (if any) thumb is touched by the given x-coordinate.
     * @param touchX The x-coordinate of a touch event in screen space.
     * @return The pressed thumb or null if none has been touched.
     */
    private Thumb evalPressedThumb(float touchX) {
            Thumb result = null;
            boolean minThumbPressed = isInThumbRange(touchX, normalizedMinValue);
            boolean maxThumbPressed = isInThumbRange(touchX, normalizedMaxValue);
            if (minThumbPressed && maxThumbPressed) {
                    // if both thumbs are pressed (they lie on top of each other), choose the one with more room to drag. this avoids "stalling" the thumbs in a corner, not being able to drag them apart anymore.
                    result = (touchX / getWidth() > 0.5f) ? Thumb.MIN : Thumb.MAX;
            }
            else if (minThumbPressed) {
                    result = Thumb.MIN;
            }
            else if (maxThumbPressed) {
                    result = Thumb.MAX;
            }
            return result;
    }

    /**
     * Decides if given x-coordinate in screen space needs to be interpreted as "within" the normalized thumb x-coordinate.
     * @param touchX The x-coordinate in screen space to check.
     * @param normalizedThumbValue The normalized x-coordinate of the thumb to check. 
     * @return true if x-coordinate is in thumb range, false otherwise.
     */
    private boolean isInThumbRange(float touchX, double normalizedThumbValue) {
            return Math.abs(touchX - normalizedToScreen(normalizedThumbValue)) <= thumbHalfWidth*2;
    }

    /** 
     * Sets normalized min value to value so that 0 <= value <= normalized max value <= 1.
     * The View will get invalidated when calling this method. 
     * @param value The new normalized min value to set.
     */
    private void setNormalizedMinValue(double value) {
            normalizedMinValue = Math.max(0d, Math.min(1d, Math.min(value, normalizedMaxValue)));
            invalidate();
    }

    /** 
     * Sets normalized max value to value so that 0 <= normalized min value <= value <= 1.
     * The View will get invalidated when calling this method. 
     * @param value The new normalized max value to set.
     */
    private void setNormalizedMaxValue(double value) {
            normalizedMaxValue = Math.max(0d, Math.min(1d, Math.max(value, normalizedMinValue)));
            invalidate();
    }
    
    /**
     * Converts a normalized value to a Number object in the value space between absolute minimum and maximum.
     * @param normalized
     * @return
     */
    @SuppressWarnings("unchecked")
    private T normalizedToValue(double normalized) {
            return (T) numberType.toNumber(absoluteMinValuePrim + normalized * (absoluteMaxValuePrim - absoluteMinValuePrim));
    }
    
    /**
     * Converts the given Number value to a normalized double.
     * @param value The Number value to normalize.
     * @return The normalized double.
     */
    private double valueToNormalized(T value) {
            if (0 == absoluteMaxValuePrim - absoluteMinValuePrim) {
                    // prevent division by zero, simply return 0.
                    return 0d;
            }
            return (value.doubleValue() - absoluteMinValuePrim) / (absoluteMaxValuePrim - absoluteMinValuePrim);
    }

    /**
     * Converts a normalized value into screen space.
     * @param normalizedCoord The normalized value to convert.
     * @return The converted value in screen space.
     */
    private float normalizedToScreen(double normalizedCoord) {
            return (float) (padding + normalizedCoord * (getWidth() - 2 * padding));
    }

    /**
     * Converts screen space x-coordinates into normalized values.
     * @param screenCoord The x-coordinate in screen space to convert.
     * @return The normalized value.
     */
    private double screenToNormalized(float screenCoord) {
            int width = getWidth();
            if (width <= 2 * padding) {
                    // prevent division by zero, simply return 0.
                    return 0d;
            }
            else {
                    double result = (screenCoord - padding) / (width - 2 * padding);
                    return Math.min(1d, Math.max(0d, result));
            }
    }

    /**
     * Callback listener interface to notify about changed range values.
     * @author Stephan Tittel (stephan.tittel@kom.tu-darmstadt.de)
     *
     * @param <T> The Number type the RangeSeekBar has been declared with.
     */
    public interface OnRangeSeekBarChangeListener<T> {
            void rangeSeekBarValuesChanged(T minValue, T maxValue);
    }
    
    /**
     * Thumb constants (min and max).
     * @author Stephan Tittel (stephan.tittel@kom.tu-darmstadt.de)
     *
     */
    private static enum Thumb {
            MIN, MAX
    };

    /**
     * Utility enumaration used to convert between Numbers and doubles.
     * @author Stephan Tittel (stephan.tittel@kom.tu-darmstadt.de)
     *
     */
    private static enum NumberType {
            LONG, DOUBLE, INTEGER, FLOAT, SHORT, BYTE, BIG_DECIMAL;

            public static <E extends Number> NumberType fromNumber(E value) throws IllegalArgumentException {
                    if (value instanceof Long) {
                            return LONG;
                    }
                    if (value instanceof Double) {
                            return DOUBLE;
                    }
                    if (value instanceof Integer) {
                            return INTEGER;
                    }
                    if (value instanceof Float) {
                            return FLOAT;
                    }
                    if (value instanceof Short) {
                            return SHORT;
                    }
                    if (value instanceof Byte) {
                            return BYTE;
                    }
                    if (value instanceof BigDecimal) {
                            return BIG_DECIMAL;
                    }
                    throw new IllegalArgumentException("Number class '" + value.getClass().getName() + "' is not supported");
            }
            
            public Number toNumber(double value) {
                    switch (this) {
                    case LONG:
                            return new Long((long) value);
                    case DOUBLE:
                            return new Double(value);
                    case INTEGER:
                            return new Integer((int)value);
                    case FLOAT:
                            return new Float(value);
                    case SHORT:
                            return new Short((short)value);
                    case BYTE:
                            return new Byte((byte)value);
                    case BIG_DECIMAL:
                            return new BigDecimal(value);
                    }
                    throw new InstantiationError("can't convert " + this + " to a Number object");
            }
    }
}
